In the disk braking field, a floating type has developed wherein the braking section and the hub section are each a separate unit that are interconnected to each other in such a manner that there is some clearance between the two sections to allow them to move and to accommodate changes in physical size due to changes in temperature and stresses in the materials. This type of brake disk provides an advantage in that the braking surface of the braking section is free of distortion and remains unchanged, even when the braking section becomes thermally expanded by the heat produced by friction during brake application. With this type of construction the thermal expansion is then uniformly distributed due to the simple ring shape without having the stresses confined by the hub section.
In the prior art, the disk brake and the hub section have been joined in one instance by semi-circular concave pieces which when paired, permit relative movement between the braking section and the hub. This is described in Japanese publication to Jikkaisho, Ser. No. 60-3333.
In another type structure in the prior art, floating pins are used with a loose fit through holes provided in mutually overlapping portions of the braking and hub sections. This is described in the Japanese publication to Jikkaisho, Ser. No. 61-104842.
In each of the two prior art examples, there is generated at the point of intersection of the hub portion with the braking portion, a wedge type action which results in large surface pressure, and concern over durability of the connection. Further, where there is mutual overlapping as in the second of the two prior art techniques, there is a thicker joint and mounting space may be limited due to the overlapping portions of the joints.